Coffee roasting apparatus and method

ABSTRACT

A coffee roaster that includes a combustion chamber and a connected roasting oven in which the heating gases for roasting the coffee beans are recirculated to the combustion chamber wherein the coffee bean chaff is separated from the recirculating heating gases prior to venting to atmosphere, and an associated cooling chamber wherein the roasted coffee beans are cooled in a two-stage heating cycle wherein the cooling air is recirculated to the combustion chamber to be reheated to roasting temperatures and vented to atmosphere during the second stage of cooling. The coffee beans being de-stoned as the cooled coffee beans are conveyed from the cooling chamber to the discharge hopper.

FIELD OF THE INVENTION

[0001] This invention is directed to a coffee roasting apparatus andmethod of roasting coffee, and more specifically to an improvement ingenerating and recirculating the heating and cooling gases for effectingthe coffee roasting process in a desirous environmental manner.

BACKGROUND OF THE INVENTION

[0002] Heretofore, coffee roasting was effected merely by passing heatedcombustion gases or air over the green coffee beans positioned in arotating roasting drum or oven, wherein the heated gases passing throughthe roasting oven was exhausted to atmosphere together with coffee beanshells or chaff and/or other coffee residue. Such apparatus and methodsreleased harmful impurities and odors into the atmosphere. Accordingly,many regulations have been put in effect in an effort to control orlimit the amount of odors and impurities that coffee roasters arepermitted to exhaust to atmosphere. As a result, the conventionallyknown methods and/or apparatuses in many instances cannot meet some ofthe more rigid standards currently being put into effect.

SUMMARY OF THE INVENTION

[0003] An object of this invention is directed to a method and apparatusfor effecting the recirculation of the roasting or heating gases back tothe combustion or heating chamber after removing therefrom the coffeeshells or chaff that tend to co-mingle with the heating gases passingthrough the roasting chamber or oven.

[0004] Another object is to effect the recirculation of the coolinggases exhausting from a coffee cooling chamber back to the combustionchamber in a manner whereby the recirculating cooling gases maintain theouter surfaces of the combustion or heating chamber at a temperaturelower than that of the gases generated in the combustion chamber andwhereby the recirculated cooling gases are incrementally raised toroasting temperature.

[0005] Another object of this invention is to provide a two stagecooling cycle wherein the cooling gases are recirculated to thecombustion chamber during the first cooling cycle to be reheated toroasting temperatures, and whereby the cooling gases are diverted duringthe second stage of the cooling cycle for venting to atmosphere.

[0006] The foregoing objects and other features and advantages areattained by a coffee roasting apparatus and method that includes aburner and an associated heating or combustion chamber for generatingthe roasting or heating gases. A coffee roasting oven is connected incommunication with the combustion chamber by a conduit for directing theheating gases from the combustion chamber to the roasting oven forroasting the coffee beans deposited therein. Connected to the roastingoven is a hopper by which the coffee beans to be roasted are directed tothe roasting oven. The roasting oven is provided with a gas outlet whichis connected into communication with a fan for conveying the heatinggases and any coffee chaff carried along therewith to a cycloneseparator whereby the coffee chaffs are separated from the heatinggases. The heating gases, from which the coffee chaff has beenseparated, is then recirculated to the combustion chamber and exhaustedto atmosphere, free of any coffee chaff.

[0007] Upon completion of the roasting cycle, the roasted coffee beansin the roasting oven are transferred to a cooling chamber wherein theroasted beans are cooled in a two-phase cycle.

[0008] In the first phase of the cooling cycle, the cooling chamber isconnected in communication with a fan which, when actuated, will drawatmospheric cooling air through the cooling chamber and recirculates thesame to the combustion chamber where the cooling air is reheated toroasting temperature. In the second phase of the cooling cycle, thecooling chamber is connected into communication to a second fan whichdirects the cooling air through the cooling chamber and which issubsequently vented to atmosphere. During the second cooling phase, thecooling chamber is closed off from the first fan so that the coolinggases or air are exhausted to atmosphere free of any chaff and/or otherimpurities. As the coffee beans are cooled in the cooling chamber andconveyed by aspiration to a discharge hopper 36, the coffee beans arealso being de-stoned whereby the separated stones are directed to acollection bin for disposal.

[0009] Subsequent to the cooling phase, the roasted coffee, free of anychaff and de-stoned, is aspirated or conveyed from the cooling chamberto a discharge hopper by the suction imparted thereto by the second fanand any residual gases being discharged to atmosphere in a more purifiedstate so that the release of any coffee chaff and/or other impurities orodor to atmosphere is greatly diminished, if not eliminated.

IN THE DRAWINGS

[0010]FIG. 1 is a diagrammatic side view of a coffee roasting apparatusembodying the present invention emphasizing the roasting phase.

[0011]FIG. 2 is a view similar to FIG. 1 emphasizing the first step ofthe cooling phase.

[0012]FIG. 3 is a view similar to FIG. 2 emphasizing the second step ofthe cooling phase.

[0013]FIG. 4 is a view similar to FIGS. 1, 2 and 3 emphasizing the finalphase of the roasting cycle.

[0014]FIG. 5 is a view similar to FIGS. 1 to 4 emphasizing the step ofloading the green coffee in the roasting oven.

[0015]FIG. 6 is a detail side sectional view of the combustion chamber.

DETAILED DESCRIPTION

[0016] Referring to the drawings, there is illustrated in diagrammaticform, a coffee roasting apparatus 10 embodying the present inventionemphasizing the various steps of the roasting process. The coffeeroasting apparatus 10 illustrated in FIGS. 1 to 5 includes a combustionchamber 11 which is fired by a suitable burner 12, e.g. a gas burner forgenerating the heating gases for effecting the roasting of green coffeebeans.

[0017] The combustion chamber 11, as best seen in FIG. 6, includes anouter insulated shell or housing 13 of any suitable cross-sectionalshape which has a recirculating gas inlet 14 and a gas outlet 15exhausting to atmosphere. A damper 16 controls the exhausting of thegases from outlet 15. Disposed within the shell or housing 13 of thecombustion chamber 11 is a first and second baffle 17 and 18respectively. The first and second baffles 17 and 18 are concentric,spaced apart, and having a cross-sectional configuration that iscomplementary to that of combustion chamber 11 to define a sinuous pathor passageway 19 for the incoming recirculated heating or cooling gasesas can be best seen in FIG. 6, and as will be hereinafter described. Theoutlet 20 of the combustion chamber 11 connects to a conduit 21 fordirecting the heating gases generated in the combustion chamber 11 tothe roasting oven 22. See FIG. 1.

[0018] The roasting oven 22 is of a generally conventional type having aperforated rotating drum 22A and internal vanes 22B for tumbling thecoffee beans as the heated gases from the combustion chamber 11 passesthrough the roasting oven. Modulating dampers 23 control the amount ofheating gases allowed to pass through the roasting oven 22. The roastingoven 22 is provided with an inclined outlet or discharge 24 whichconnects to a first fan 25 by means of a conduit 26. Fan 25 is providedwith an outlet 25A connected to a duct or conduit 27 for directing theheated gases and any coffee chaffs entrained therein to a cycloneseparator 28 wherein the chaff is separated from the heating gases. Thechaff, which is separated from the heating gases within the cycloneseparator 28, will fall by gravity into a chaff chamber 29 from whichthe chaff may be removed.

[0019] The heated gases free of the coffee chaff is then directed to theoutlet 28A of the cyclone separator 28 and recirculated back to thecombustion chamber 11 as indicated by the arrow flow path 30. Theheating gases free of the residue coffee chaff is then reintroduced intothe combustion chamber 11 via the gas inlet 14 and vented through outlet15 to atmosphere free of any coffee chaff.

[0020] Upon completion of the coffee roasting operation, the roastedcoffee beans are removed from the roasting oven 22 via an oven outlet ordoor 22C, whereby the roasted beans are directed to a cooling chamber30A located below the oven outlet 22C. Within the cooling chamber 30A,as shown in FIG. 2, is a rotating perforated platform 30B for receivingthe roasted coffee beans. Invariably, small stones or pebbles tend tomix with the coffee beans when harvested, and which are required to beseparated from the roasted coffee beans. This is effected as the cooledcoffee beans are conveyed from the cooling chamber 30A to the dischargehopper 36 under a negative pressure, as will be described. Ultimately,the separated stones are directed to a de-stoning pit 31.

[0021] The cooling air entering the cooling chamber, upon the transferof the roasted coffee beans from the roasting oven 22 to the coolingchamber 30A, is induced through conduit or passageway 32 and 32A by thesuction imparted by fan 25. As best noted in FIG. 2, duct or conduit 32Aconnectes with duct or conduit 26 which connects to the inlet of fan 25.Suitable dampers 33 and 34 are disposed at the junction of conduit 32and 32A and at the junction of conduit 32A and 26 respectively, as notedin FIG. 2.

[0022] As best seen in FIG. 2, the dampers 33 and 34 are in a closed andopen position respectively, so that the cooling air is directed from thecooling chamber 30A, through fan 25 and recirculated back to thecombustion chamber 11 as indicated in FIG. 2. During the cooling cyclejust described, the modulating dampers 23 in conduit 21 are closed sothat the recirculated air is exhausted to atmosphere via outlet 15 asnoted in FIG. 2, as clean air, i.e. free of any substantial coffee beanresidue.

[0023] As noted in FIG. 2, the cooling medium, being recirculated to thecombustion chamber 11, is directed in a sinuous path within thecombustion chamber 11, as indicated at 19, whereby the recirculatedcooling medium is incrementally reheated to roasting temperatures, withthe cooler incoming recirculating cooling medium tempering the outersurfaces of the combustion chamber 11. As the recirculating cooling airadvances through the sinuous path 19 and make contact with the surfacesof the innermost baffle 18, the temperatures of the recirculating air isincrementally raised to roasting temperatures whereby the heated air maybe redirected to the roasting oven 22 to effect a subsequent roastingcycle or exhausted to atmosphere via the gas outlet or chimney 15, freeof any residue or entrained chaff, the chaff being separated beingseparated from the recirculating gases in the cyclone separator 28 andcollected in the chaff chamber 29.

[0024] The cooling cycle described above, and as shown in FIG. 2,comprises the first phase of a two-phase cooling cycle, and which firstphase has a relatively short duration, e.g. approximately one minute.

[0025]FIG. 3 emphasizes the second stage of the cooling cycle. Duringthis phase, damper 33 is shifted to a position wherein the damper 33closes off conduit 32A from conduit 32 so that the cooling air exitingthe cooling chamber 30A are directed via conduit 32 to a second fan 35,whereby the cooling medium is vented to atmosphere as clean air, asnoted in FIG. 3. This second cooling phase may last 7 or 8 minutes.

[0026] Upon completion of the first and second cooling phases, thecooled coffee beans in the cooling chamber 30A, are de-stoned as thecoffee beans are conveyed by aspiration from the cooling chamber 30A toa discharge hopper 36. The coffee beans, being lighter than the stonesor pebbles, are aspirated upwardly to the hopper 36 as the heavierstones or pebbles are dropped into the de-stoning pit 31 from which theycan be removed. The hopper 36 is provided with a controlled dischargeopening 37 form which the roasted coffee beans may be removed and/orpackaged.

[0027] Any residual gases entrained with the roasted coffee as thecoffee beans are conveyed to the discharge hopper 36 by aspirationinduced by fan 35 are vented or sucked out of the discharge hopper viaoutlet 36A and directed through suitable ducts (shown in dash lines) toan inlet 38 connected in communication with conduit 32 adjacent to theinlet of fan 35. A two-way control damper 39 is provided to close offthe inlet 38 from conduit 32 so that a negative pressure is induced intothe discharge hopper 36 whereby fan 35 is vented to atmosphere as bestseen in FIG. 4.

[0028] During the second cooling phase herein described, the damper 39is shifted to close off inlet 38 so that the cooling medium in thecooling chamber 30A is directed via conduit 32 to the inlet of fan 35for venting to atmosphere as hereinbefore described. (See FIG. 3).

[0029]FIG. 5 emphasizes the manner in which the green coffee beans areinitially loaded into the roasting oven 22. This is attained by anoperator dumping a load of green coffee beans into a loading hopper 40.From the loading hopper, the coffee beans are aspirated by a suction ornegative pressure to second hopper 41 which has a controlled dischargeport 42 disposed in communication with the roasting oven 22. A damper orvalve 43 controls the opening and closing of the discharge port 42 so asto control the amount of green coffee beans to be placed into theroasting oven 22.

[0030] In operation, a predetermined amount of green coffee beans areloaded into the roasting oven 22, as hereinabove described. The roastingcycle is started as the burner 12 is actuated. As the combustion gasesare generated, the gases are directed through conduit 21 to the roastingoven 22, the amount of heating or combustion gases directed to theroasting oven 22 being modulated by modulating damper 23. Within theroasting oven 22, the coffee beans are tumbled as they are being roastedwhereby the coffee bean chaff or shell is separated from the coffeebean. The heating or combustion gases together with the coffee beanchaff exit the roasting oven 22 via oven discharge outlet 24 and areconveyed by conduit 26 to the inlet of fan 25 whereby the heating gasesand entrained chaff are directed via conduit 27 to a cyclone separator28.

[0031] Within the cyclone separator 28, the chaff is separated from therecirculating gases whereby the chaff drops to a chaff chamber 29 as theheating gases, free of any chaff, is directed to the inlet 14 forrecirculating through the combustion chamber 11 or vented to atmospherethrough inlet 15, free of any chaff. Generally, the roasting cycle maylast for approximately fifteen minutes, but may vary depending upon theamount of coffee beans loaded into the roasting oven 22.

[0032] Upon completion of the roasting cycle, the roasted coffee beansare directed to a cooling chamber 30A whereby the roasted coffee beansare cooled in a two-phase cooling cycle. Upon the roasted coffee beansbeing cooled, the coffee beans are de-stoned, i.e. that any stones orpebbles that are co-mingled with the coffee beans during the harvestingthereof are separated from the roasted coffee beans as hereinbeforedescribed. The separated stones or pebbles are directed to a de-stoningpit 31.

[0033] During the first phase of the cooling cycle, the cooling airunder the action of fan 25 is sucked into the cooling chamber anddirected through conduits 32 and 32A to the inlet of fan 25 andrecirculated back to the combustion chamber 11, as best seen in FIG. 2.A damper or control valve 33 is positioned at the junction betweenconduit 32 and conduit 32A for directing the cooling air flow throughfan 25 to the combustion chamber 11, as shown in FIG. 2. During thefirst cooling phase, the cooling air is recirculated to the combustionchamber 11 and exhausted to atmosphere through chimney or outlet 15 asclean gases. Generally, the first cooling phase may have a duration ofapproximately one minute, but may vary.

[0034] During the second cooling phase, damper 33 is shifted to aposition whereby conduit 32A is shut off from communication with conduit32 and control valve or damper 39 positioned to seal off inlet 38 sothat the cooling air passing through the cooling chamber 30A is directedthrough fan 35 for venting to atmosphere, devoid of any entrainedresidue chaff, pebbles and the like. The second cooling phase may extendfor approximately seven minutes, depending upon the amount of roastedcoffee beans being cooled within the cooling chamber 30. See FIG. 3.

[0035] The final cycle comprises the conveyance of the roasted coffeebeans, which have been cooled, from the cooling chamber to the dischargehopper 36. This is attained by aspiration or a negative pressure imposedon the discharge hopper 36. This is attained by fan 35 through inlet 38disposed in communication with the discharge hopper, and which fan 35 isvented to atmosphere, as best seen in FIG. 4. In this phase, damper 39seals conduit 32 from inlet 38. De-stoning occurs as the cooled coffeebeans are aspirated from the cooling chamber 30A to the discharge hopper36.

[0036] The roasted coffee beans loaded into the discharge hopper 36 maybe withdrawn as desired through a controlled discharge port 37.

[0037] It will be understood that suitable controls may be provided toactuate the component parts in a predetermined sequence so that theentire roasting operation may be automatically accomplished.

[0038] From the foregoing, it will be apparent that the roasting gasesare permitted to be vented to atmosphere free of any residual mattersuch as coffee bean chaff, and/or other impurities commonly associatedwith the roasting of coffee beans.

[0039] While the present invention has been described with respect to aparticular apparatus and method, variations and modifications thereofmay be made without departing from the spirit and scope of thisinvention.

What is claimed is:
 1. A coffee bean roasting apparatus comprising: acombustion chamber for generating heating gases, a roasting ovenconnected in communication with said combustion chamber whereby theheating gases are directed to said oven, means for recirculating theheating gases flowing through said roasting oven back to the combustionchamber free of any coffee bean residue.
 2. A coffee bean roastingapparatus as defined in claim 1, and said combustion chamber includingspaced apart baffles within said combustion chamber defines a sinuouspath for incrementally reheating a recirculating cooling medium toroasting temperature.
 3. A coffee bean roasting apparatus as defined inclaim 1 wherein said heating gas recirculation means includes a suctionfan having an inlet and an outlet, said in let being disposed incommunication with said roasting oven, a separator, said outlet of saidfan being connected in communication with said separator, whereby saidfan draws said heating gases and any entrained chaff from said oven andconveys said heating gases and entrained chaff to said separator, saidchaff being separated from said heating gases in said separator wherebysaid heating gases free of chaff is recirculated to said combustionchamber.
 4. A coffee bean roasting apparatus as defined in claim 1 andincluding a cooling chamber for cooling the coffee beans after beingroasted in said oven, means connected to said cooling chamber foreffecting a first phase cooling of said roasted coffee beans therein,and means connected to said cooling chamber for effecting a second phasecooling of said roasted coffee beans therein.
 5. A coffee roastingapparatus as defined in claim 4 and including means for de-stoning saidcooled coffee beans.
 6. A coffee roasting apparatus comprising: acombustion chamber, a burner for generating heating gases within saidcombustion chamber, spaced apart baffles disposed within said combustionchamber to define a sinuous recirculation gas path, a gas inlet and agas outlet connected to said combustion chamber, a roasting oven, a ductconnecting said combustion chamber in communication with said roastingoven for directing heating gases from said combustion chamber to saidroasting oven, said roasting oven including a perforated rotating drum,a separator, means for directing the heating gases in said oven andentrained coffee chaff exiting said oven during the roasting cycle tosaid separator wherein said chaff is separated from the heating gases,means for directing said heating gases free of any chaff back to saidcombustion chamber, a cooling chamber for receiving the roasted coffeebeans when roasting of the coffee beans has ended, a first phase coolingmeans connected to said cooling chamber for drawing a cooling gasthrough said cooling chamber and recirculating said cooling medium tosaid combustion chamber, and a second phase cooling means connected tosaid cooling chamber for venting said cooling medium directly toatmosphere.
 7. A coffee roasting apparatus comprising: a combustionchamber, a burner for generating combustion gases within said combustionchamber, said combustion chamber having a recirculating gas inlet andgas outlet exhausting to atmosphere, baffle means disposed within saidcombustion chamber to define a sinuous flow path, a coffee roastingoven, a connecting conduit connecting said combustion chamber incommunication with said coffee roasting oven, a modulating damperdisposed in said connecting conduit, said roasting oven including arotating drum and a gas outlet, a suction fan connected in communicationwith said oven gas outlet, said suction fan having an outlet, aseparator, a conduit connecting said outlet of said suction fan incommunication with said separator, said separator separating any coffeechaff entrained in the heating gases being recirculated, and means fordirecting the heating gases exiting said separator back to saidcombustion chamber for venting to atmosphere free of any coffee chaff.8. A coffee roasting apparatus as defined in claim 7 and including: acooling chamber for receiving the roasted coffee beans from said ovenupon completion of the roasting period, means for connecting saidsuction fan in communication with said cooling chamber for drawingcooling air into said cooling chamber and closing said suction fan outof communication with said oven, whereby said suction fan effectsrecirculation of said cooling air to said combustion chamber, saidcooling air being reheated to roasting temperature as it flows throughsaid sinuous path.
 9. A coffee roasting apparatus as defined in claim 8and including: means for aspirating the cooled coffee beans from saidcooling chamber, and a discharge hopper connected with said coolingchamber for receiving said aspirated cooled coffee beans, whereby saidcooled coffee beans are de-stoned.
 10. A method of roasting coffee beanscomprising the steps of: generating heating gases in a combustionchamber, directing said heating gases to a roasting oven containing apredetermined amount of coffee beans to be roasted, tumbling said coffeebeans within said oven as said coffee beans are being roasted andseparating the roasting coffee beans from its chaff, directing saidheating gases and entrained coffee bean chaffs to a separator toseparate the chaff from said heating gases, and recirculating theheating gases free of said chaff to said combustion chamber for ventingto atmosphere free of chaff.
 11. A method as defined in claim 10 andincluding the steps of: removing the roasted coffee beans from theroasting oven and placing said roasted coffee beans in a coolingchamber, effecting the cooling of said roasted coffee beans in twoconsecutive phases, recirculating the cooling gases during the first ofsaid cooling phases to said combustion chamber, and venting the coolinggases during the second of said cooling phases to atmosphere.
 12. Themethod as defined in claim 10 and including the step of de-stoning saidroasted coffee beans subsequent to said cooling phases.
 13. The methodas defined in claim 10 and including the step of de-stoning said cooledcoffee beans as said coffee beans are transferred from said coolingchamber to a discharge hopper.
 14. A method of roasting coffee beanscomprising the steps of: generating heating gases in a combustionchamber, directing said heating gases to a roasting oven containing apredetermined amount of coffee beans whereby said coffee beans areroasted, removing said heating gases and any coffee bean chaff entrainedfrom said roasting oven, and separating the coffee bean chaff from saidheating gases prior to said heating gases being recirculated to saidcombustion chamber.
 15. A method of roasting coffee beans as defined inclaim 14 and including the steps of: removing the roasted coffee beansfrom the roasting oven, effecting the cooling of said roasted coffeefirst by directing cooling atmospheric air over said roasted coffeebeans and recirculating said cooling air to the combustion chamber, andthereafter directing said cooling atmospheric air and venting the sameto atmosphere.
 16. A method of roasting coffee beans as defined in claim15 and including the step of de-stoning said roasted coffee beanssubsequent to the cooling thereof.
 17. A method of roasting coffee beansas defined in claim 10 and including the step of de-stoning the roastedcoffee beans by aspirating said coffee beans whereby the heavier stonesare separated from said roasted coffee beans by gravity.